Apparatus for denesting and feeding cartons to a conveyor

ABSTRACT

Apparatus for sequentially removing articles from a stack of nested articles and for controlling their movement to a location remote from the stack. The apparatus is particularly suited for denesting and feeding large multiple cell cartons such as eighteen cell cartons to a conveyor for subsequent printing. The cartons are placed in a vertical stack and the stack of nested cartons is supported by a set of rotary brushes on opposite sides at the bottom of the stack. The cartons are preseparated and sequentially fed by a second set of rotary brushes from the bottom of the stack to a denesting station. The height of the stack of cartons at the denesting station is sensed by a photoelectric eye for controlling the rotation of the sets of brushes and the feed of cartons to the denesting station. A pair of counter-rotating feed screws having multiple operating sections denest the cartons at the denesting station and sequentially feed them to a conveyor.

This is a divisional of copending application Ser. No. 045,504, filed onMay 4, 1987, now U.S. Pat. No. 4,867,632.

BACKGROUND OF THE INVENTION

This invention relates to an apparatus and method for sequentiallyremoving articles from a stack of nested articles and for controllingtheir movement to a location remote from the stack.

The method and apparatus of the present invention is particularly suitedfor denesting and feeding large multiple cell cartons, such as eighteencell egg cartons, to a conveyor for subsequent printing operation.Examples of eighteen cell egg cartons are disclosed in the U.S. Pat.Nos. 4,625,905, and 4,625,906 of Raj K. Mangla. Cartons of this type maybe made of wood pulp or, more recently, formed from sheets of plasticmaterial by a thermoforming process. After the cartons have been formed,it is the practice to print the top surface of the cover with a suitablewording and/or design. Eighteen cell egg cartons are substantiallylarger than twelve cell egg cartons and thus are more difficult tohandle on an automatic assembly line. After the cartons have beenthermoformed they are nested one within the other into high verticalstacks where they are stored for subsequent operations. In order toperform the subsequent operations it is necessary to denest the cartonsfrom the stacks. This operation has been performed in the past by theuse of a pair of feed screws through which the cartons are sequentiallyfed. The feed screws had the same thread and rotated in the samedirection. Such feed screws have been satisfactory for denesting twelvecell egg cartons, however, they have left considerable to be desiredwith regard to denesting eighteen cell egg cartons.

It is an object of the present invention to provide a method andapparatus for sequentially removing articles from a stack of nestedarticles and for controlling their movement to a location remote fromthe stack and doing so in a manner suitable for automation.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention there is provided amethod for sequentially removing articles from a stack of nestedarticles and for controlling their movement to a location remote fromthe stack. The method comprises the steps of placing a plurality ofnested articles in a vertical stack and supporting the stack of nestedarticles on opposite sides at the bottom of the stack. The methodfurther includes preseparating and sequentially feeding the nestedarticles at the bottom of the stack to a denesting station and sensingthe height of the stack of articles at the denesting station forcontrolling the feed of articles to the denesting station and denestingthe articles at the denesting station and sequentially feeding them to aconveyor.

It is a further object of the invention to provide a method fordenesting and feeding cartons to a conveyor including the steps ofplacing a plurality of nested cartons in a vertical stack and supportingthe stack of nested cartons on opposite sides at the bottom of thestack. The method further includes the steps of preseparating andfeeding the nested cartons from the bottom of the stack to a pair offeed screws having grooves of opposite hand positioned in a spacedrelation to receive the opposite ends of the cartons, the axis of thefeed screws being tilted with respect to the vertical axis of the stackto compensate for the lead angle of the feed screws so that the cartonsride flat in the grooves of the feed screws to allow a wider variationand thickness of the cartons at the screw pick up points. The methodfurther includes rotating the feed screws in counter directions andengaging a plurality of the cartons in a first section of the feedscrews having a pitch matching the spacing of the nested cartons fordistributing the weight of the stack of cartons over a plurality ofcartons rather than only on the bottom carton of the stack to avoiddistortion of the carton and permitting the lead edge of the feed screwsto enter the nested stack without damaging the cartons. The methodfurther includes moving the cartons into a second section of the feedscrews having an increased pitch serving to separate the bottom-mostcarton from the stack thereby causing the carton to tip slightly wherebythe carton is out of parallel with the conveyor upon which the carton isto be placed The method further includes moving the carton to a thirdsection of the feed screws where the groove pitch is zero for 120° ofscrew rotation to cause the carton to level out parallel with theconveyor upon which the carton is to be placed and moving the carton toa fourth section of the feed screws where the pitch is substantiallyequal to the pitch of the first section of the feed screws therebygiving the carton a downward kick onto the conveyor.

It is a further object of the invention to provide apparatus forsequentially removing articles from a stack of nested articles and forcontrolling their movement to a location remote from the stack. Theapparatus comprises supporting means for supporting a plurality of thenested articles in a vertical stack and feeding means positioned beneaththe supporting means for preseparating and sequentially feeding thenested articles from the bottom of the stack. The apparatus furtherincludes denesting means positioned beneath the feeding means to receivethe nested articles from the feeding means, the denesting meanscomprising a pair of feed screws positioned in spaced relation toreceive opposite ends of the articles for support therebetween, each ofthe feed screws being of the opposite hand, and means forcounter-rotating the feed screws.

In accordance with one aspect of the invention, the supporting meanscomprises first rotary brush wheels positioned in spaced relation toreceive opposite ends of the articles for support therebetween and thefeeding means comprises second rotary brush wheels positioned in spacedrelation to receive opposite ends of the articles from the first rotarybrush wheels. Means is also provided for rotating the second rotarybrush wheels at a higher speed than the first rotary brush wheelswhereby as the stack of articles passes through the first rotary brushwheels, the second rotary brush wheels due to the higher rotationalspeed preseparate the articles in presenting them to the feed screws.

In accordance with another aspect of the invention there is providedmeans for sensing the height of the stack of articles on the feedscrews, and means responsive to the sensing means for controlling thedrive of the first and second brush wheels whereby a substantiallyuniform weight of articles rests on the feed screws during the operationof the apparatus thereby reducing the deformation of the articles fromthe weight of the stack.

In accordance with a further aspect of the invention each of the feedscrews is provided with four different operating sections, the pitch inthe first section of each feed screw matching the spacing of the nestedarticles, the length of the first section of each feed screw beingsufficient to engage a plurality of the nested articles before anyseparation action of the feed screws begins so as to distribute theweight of the articles over a plurality of articles rather than only thebottom article of the stack thereby avoiding distortion of the articlesand permitting the leading edge of the feed screws to enter the nestedstack. Each of the feed screws has a second section having an increasedpitch for separating the bottom-most article of the stack and each ofthe feed screws has a third section in which the groove pitch is zerofor 120° rotation. Each of the feed screws has a fourth section with apitch approximately equal to the pitch of the first section, the axis ofeach feed screw being inclined with respect to the vertical axis of thestack so that the grooves in the first section are substantiallyhorizontal whereby the articles ride substantially flat in the grooves.

The foregoing and other objects, features and advantages of theinvention will be better understood from the following, more detaileddescription and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of apparatus for sequentially removingarticles from a stack of nested articles and for controlling theirmovement to a location remote from the stack embodying the presentinvention.

FIG. 2 is a front elevational view taken along the line 2--2 in FIG. 1.

FIG. 3 is a horizontal sectional view taken along the line 3--3 in FIG.2.

FIG. 4 is a fractional sectional view on enlarged scale taken along theline 4--4 in FIG. 2.

FIG. 5 is a side elevation of the feed screw taken along the line 5--5in FIG. 4.

FIG. 6 is a sectional view taken along the line 6--6 in FIG. 5.

FIG. 7 is an elevational view of a feed screw used in the prior art; and

FIG. 8 is a diagrammatic view illustrating the upper and lower brushassemblies a photoelectric eye for sensing the height of the stack ofcartons and controlling the brush drive.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As pointed out above, the present invention is directed to appartus forsequentially removing articles from a stack of nested articles and forcontrolling their movement to a location remote from the stack Thepreferred embodiment illustrated in the drawings will be described inconnection with apparatus for denesting and feeding egg cartons to aconveyor for subsequent printing. Egg cartons come in both 12-cell and18-cell sizes. The 18-cell sizes are particularly difficult to denestand feed due to their large size The present invention is particularlysuited for handling 18-cell egg cartons. As shown in FIGS. 1 and 2, theapparatus 10 is mounted on a frame F of a conveyor 12 which is adaptedto transport cartons C sequentially to a printing station where the topsor covers of the cartons are provided with the appropriate printing. Asmay be seen at the top of FIGS. 1 and 2, the apparatus 10 has beenprovided with a stack S of nested cartons C which it is desired todenest and feed to the conveyor 12. The conveyor 12 includes a table 14having a slot 14a extending lengthwise thereof and through which isadapted to extend a conveyor chain 16. The conveyor chain 16 is providedwith upstanding lugs 16a which are adapted to engage the trailing end ofa carton C and move it lengthwise of the conveyor 12 to a printingstation, not shown. The lugs 16 a are disposed at spaced locations alongthe conveyor chain 16 and the conveyor chain 16 is driven from asprocket wheel 18 mounted on a shaft 20 which in turn is driven from apulley 22 and a belt 24 connected to a suitable driving motor, notshown. Also mounted on the shaft 20 is a pulley 26 that is adapted tosupply the driving power to the denesting apparatus as hereinafterdescribed.

As shown in FIGS. 1 and 2, the cartons C are placed in the apparatus 10in a vertical stack S and supported by a U-shaped guide 28 mounted on avertical frame F1. A pair of guide shoes 29, one on each side of thestack S are provided at the hinge area to help stabilize the verticalstack, one of the guide shoes 29 is shown in FIG. 1. At the bottom ofthe apparatus 10 are located two feed screws 30 and 32, one at each endof the carton C at the hinged area. This is best shown in FIGS. 2 and 3.The feed screws 30 and 32 are of opposite hand and are counter-rotatingas distinguished from prior egg carton denesting apparatus where thefeed screws rotated in the same direction. A prior art feed screw isshown in FIG. 7. The purpose of the counter-rotation and the design ofthe novel feed screws will hereinafter be described. The drive for thecounter-rotating feed screws 30 and 32 is derived from the pulley 26 onthe continuously driven shaft 20 of the conveyor 12, FIG. 1. A belt 34connects the driving pulley 26 with a pulley 36 mounted on a shaft 38extending from a right angle gear box 40 on the apparatus 10, FIG. 3.The opposite end of shaft 38 is provided with a bevel gear 42 which isadapted to mesh with a bevel gear 44 mounted on a shaft 46 which isjournaled between the side frames Fl, Fl of the apparatus 10. The endsof the shaft 46 are each provided with pulleys 48 and 50 over which passdrive belts 52 and 54 respectively. The belt 52 passes over a pulley 56on the end of a shaft 58 extending from a right angle gear box 60. Theopposite end of the shaft 58 is provided with a bevel gear 62 which isadapted to mesh with a bevel gear 64 fixed to the shaft 66 of the feedscrew 30. As shown in FIG. 4, the shaft 66 may be keyed to the feedscrew 30 by a key 66a or other suitable means. The drive for the feedscrew 32 is provided in similar manner. As shown in FIG. 3 the belt 54passes over a pulley 70 mounted on one end of a shaft 72 extending froma right angle gear box 74. The opposite end of the shaft 72 is providedwith a bevel gear 76 which in turn meshes with a bevel gear 78 fixed toa shaft 80 of the feed screw 32.

From the foregoing it will be seen that the drive for both of the feedscrews 30 and 32 is derived from the belt 34 pulley 36 and shaft 38 tothe right angle gear box 40. The right angle gear box 40 drives theshaft 46 having the pulleys 48 and 50 at its opposite ends. The drivefor the feed screw 30 is derived from the pulley 48, belt 52, pulley 56,shaft 58 and the right angle gear box 60. The drive for the feed screw32 is derived from the pulley 50, the belt 54, the pulley 70, the shaft72 and the right angle gear box 74. The directions of rotation of thevarious parts are illustrated in FIG. 3 by the respective arrowsassociated with those parts. It will be noted that the resultingdirection of rotation of the feed screw 30 is in a counterclockwisedirection while the resulting direction of rotation of the feed screw 32is in a clockwise direction.

As pointed out above, the cartons C are placed in the denestingapparatus 10 in a vertical stack S. At the bottom of the apparatus 10are located the two feed screws 30 and 32, on at each end of the cartonat the hinge area as shown in FIGS. 2 and 3. The novel feed screws 30and 32 are the same except that they are of the opposite hand since theyrotate in opposite directions. A detailed description of the feed screwswill now be given in connection with feed screw 30 illustrated in FIGS.4-6. Each of the feed screws 30 and 32 is a single component with fourdifferent operating sections I-IV. The pitch in the first section I ofeach screw is so designed as to match the spacing of the nested cartonsC. Four or five cartons are engaged in the screws 30 and 32 before anyseparation action of the screws begins. This serves the purpose ofdistributing the weight of the stack of the cartons over four or fivecartons rather than only the bottom carton of the stack. In this way,distortion or bending of the carton, which is soft, is avoided, and thelead edge of the screw can enter the nested stack without malfunction. Iwill also be noted in FIG. 5 that the axis of the feed screw 30 istilted from the vertical so that the grooves in section I arehorizontal. This compensates for the lead angle of the screw 30 andresults in the cartons riding flat in the groove and allows a widervariation in thickness of the carton at the screw pick up points.

The second section II of the screw 30 has an increased pitch whichserves to separate the bottom-most carton from the stack, because of thelead angle of the pitch, the carton is tipped slightly while travelingthrough this portion of the screw and is not parallel with the conveyordeck 14 upon which it will be placed. In the third section III of thescrew 30, the groove pitch is zero for 120° of screw rotation. Thiscauses the carton to level out parallel with the conveyor deck 14, andalso exerts the force necessary to break loose the outermost row ofcells in the egg carton C. Heretofore, this has been a problem inobtaining satisfactory high-speed 18-cell denesting. The fourth sectionIV of the screw 30 is a slight pitch, preferably equal to the firstpitch, which gives the carton a slight downward "kick" onto the conveyor12 below. As pointed out above and as illustrated in FIGS. 2 and 3, thescrews 30 and 32 are counter-rotating as opposed to prior egg cartondenesters where the screws rotated in the same direction. An example ofa prior art feed screw is illustrated in FIG. 7. It will be noted thatthe axis of the prior art screw is vertical and is not tilted at anangle as shown in the novel screw 30 illustrated in FIG. 5. By reason ofthe novel feed screw design in the present invention and bycounter-rotating the feed screws, the opposing faces of the feed screws30 and 32, FIGS. 2 and 3, where the cartons are located, are parallel,eliminating a twisting force that is exerted on the carton in the priordenesters during the travel of the cartons through the screw grooves.

Referring to FIGS. 1 and 2, it will be seen that in apparatus 10 thereis located a short distance above the feed screws 30 and 32, forexample, about 12-14 inches, two sets of rotary brush wheels and eachset comprising two pairs of rotary brush wheels with one brush wheel ineach pair engaging one side of the cartons C. For example, as shown inFIGS. 1 and 2 the top set of brushes comprises a pair of brushes 80, 80disposed on one side of the stack of cartons and a pair of brushes 82,82 on the opposite side of the stack. Beneath the top set of rotarybrush wheels is a set of lower brush wheels comprising two pairs ofbrushes 84, 84 and 86, 86. As may be seen in FIG. 2, the top set ofbrushes 80 and 82 are adapted to isolate all of the apparatus below itfrom the weight of the stack of incoming cartons. It also will be notedthat the pair of brushes 80,80 in the top set rotate in the oppositedirection from the pair of brushes 82,82 in the top set of brush wheelsIt will also be noted that the pair of brushes 84,84 in the lower set ofbrush wheels rotate in the counter direction to the pair of brush wheels86,86 in the lower set of brush wheels.

The drive for the upper and lower sets of brush wheels is provided by amotor and clutch-brake mechanism 90 having an output pulley 92 overwhich passes a drive belt 94. The belt 94 drives a pulley 96 mounted ona shaft 98 on which are mounted the pair of brush wheels 84,84. The endsof the shaft 98 are journeled in an upstanding support member 100. Asshown in FIG. 2, the belt 94 also passes over a pulley 102 mounted onshaft 104 on which are mounted the pair of brush wheels 86,86. Theopposite ends of the shaft 104 are journaled in an upstanding support106. The drive for the top set of brushes is also derived from the motorand clutch-brake unit 90. As may be seen in FIG. 1 a second pulley 100is mounted on the shaft 98 adjacent the pulley 96. A belt 110 passesover pulley 100 and also over a pulley 112 mounted on one end of a shaft114. The pair of rotary brushes 80,80 are mounted on the shaft 114, theopposite ends of which are journeled in the upstanding support 100. Asecond pulley 116 is mounted on the shaft 104 behind pulley 102, FIG. 2.A belt 118 passes over the pulley 116 and also over a pulley 120 mountedon a shaft 122. The upper pair of brushes 82,82 are mounted on the shaft122, the opposite ends of which are journeled in the upstanding support106.

While the top set of rotary brushes 80,80 and 82,82 are driven from thesame motor 90 as the bottom or lower set of rotary brushes 84,84 and86,86 they are not driven at the same speed. It will be noted in FIG. 2that the drive pulleys 96 and 102 for the lower brush pairs 84 and 86have a smaller diameter than the drive pulleys 112 and 120 for the upperbrush pairs 80 and 82. Thus the brushes 84 and 86 in the lower brush settravel at a higher speed than the brushes 80 and 82 in the top brushset. The purpose of this will now be explained. As the stack of cartonspasses through the top set of brush wheels 80, 82, the lower set ofbrush wheels 84 and 86, which have a high rotational speed,pre-separates the cartons, "fluffing" those and presenting them to thefeed screws 30 and 32. In process handling and storage, there is astrong tendency for the stack of cartons S to "lock" together, makingthem difficult to separate by feed screws alone. This pre-feederoperation uniformly breaks this locking force holding the cartonstogether in the stack to facilitate the denesting operation of the feedscrews.

As pointed out above, the top and lower brush sets, 80, 82 and 84, 86are driven from a common motor 90 but at different speeds. The motor 90includes a clutch-brake mechanism. Such units are availablecommercially. An example of one such suitable unit is model5IK90GS-A2FUL/5CGS-0l/5GS36K manufactured by Oriental Motor Company. Theclutch-brake mechanism is adapted to be operated by a photoelectric eyesensor 130 which is electrically connected to the motor brake unit 90 asindicated by the broken line 132, FIG. 8. As shown in FIGS. 1, 2 and 8,the sensor 130 is mounted on the frame of the apparatus 10 adjacent oneside of the stack S of cartons. The sensor 130 is positioned above thefeed screws 30, 32 and beneath the lower set of rotary brush wheels 84,86. As may be seen in FIGS. 1, 2 and 8 the sensor 130 is adapted tosense the height of the stack of cartons on the feed screws 30, 32. Thesensor 130 turns on and off the brush drive from motor 90 through itsclutch-brake mechanism. When the stack of cartons on the feed screws isabove the level of the sensor 130 the clutch brake mechanism is actuatedto turn off the brush drive from motor 90 and avoid further feeding ofcartons from the upper stack. When the sensor 130 is above the height ofthe stack of cartons on the feed screws 30, 32, the sensor actuates theclutch-brake mechanism turning on the brush drive from motor 90 and thusfeeds additional cartons from the bottom of the stack to the feed screws30, 32. Thus it will be seen that the sensor 130 enables a substantiallyuniform weight of cartons to rest on the feed screws 30, 32 at alltimes, further reducing the deformation of cartons from the weight ofthe stack. It will also be noted that the top brush set including thepairs 80,80 and 82,82 of brushes isolates all of the mechanism below itfrom the weight of the incoming stack of cartons. This permitsautomation of the placement of nested cartons in the printing linedenester.

From the foregoing it will be seen that in operation of the apparatus10, a stack of nested cartons is placed on the top set of rotary brushrolls 80, 82. The sensor 130 actuates the clutch-brake mechanism toenable the drive motor 90 to drive both the upper and lower brush setsthus feeding the cartons downwardly through the apparatus onto the feedscrews 30 and 32. As shown in FIG. 8 the lower set of brush rolls 84, 86by reason of their higher rotational speed from that of the upper set ofbrush wheels 80,82 pre-separate the cartons, "fluffing" those andpresenting them to the feed screws 30, 32. When the height of the stackof cartons on the feed screws is above the sensor 130, the sensor 130turns off the brush drive through the clutch-brake mechanism 80 thusstopping further feed of cartons from the brush sets. When the cartons Creach the feed screws 30, 32, the ends of the cartons at the hinge areaenter the grooves in the counter-rotating feed screws 30, 32. The axesof the feed screws are tilted with respect to the vertical so that thegrooves in section I of the feed screws are horizontal. This compensatesfor the angle of the screws and results in the cartons C riding flat inthe grooves thereby allowing a wider variation in thickness of thecartons at the screw pickup points. The cartons are successively feddownwardly through the grooves of the feed screws 30 and 32 passingthrough the section I and thereafter entering the second section IIwhich has an increased pitch which serves to separate the bottom-mostcarton of the stack and because of the lead angle of the pitch, thecarton tips slightly while traveling through this section of the screwand is not parallel with the conveyor 12 upon which it will be placed.As pointed out above the third section III of the screw has a groovepitch of zero for 120° of screw rotation thus causing the carton tolevel out parallel with the conveyor deck and also exerts the forcenecessary to break loose the outermost row of cells in the egg carton.The fourth section IV of the screw is a slight pitch, preferably equalto the first pitch in section I, and this gives the carton a slightdownward "kick" onto the conveyor 12 below.

When the cartons C arrive on the conveyor 12 as shown in FIGS. 1 and 2,the ends of the cartons C are engaged by the lug 16a on the conveyorchain 16 and are moved in succession to a location remote from the stackfor subsequent printing or other operations. With an apparatus of thetype described herein it has been possible to denest egg cartons of the18 cell size from a stack of cartons at a rate of about 400 per minuteand deliver them to a conveyor for subsequent printing.

While there has been described a preferred embodiment of the invention,it will be understood that further modifications may be made withoutdeparting from the spirit and scope of the invention as set forth in theappended claims.

What is claimed is:
 1. Apparatus for sequentially removing articles froma stack of nested articles and for controlling their movement to alocation remote from the stack comprising:(a) supporting means forsupporting a plurality of the nested articles in a vertical stack; and(b) denesting means positioned beneath said supporting means to receivethe nested articles, said denesting means comprising a pair of feedscrews positioned in spaced relation to receive opposite ends of thearticles for support therebetween, each feed screw being of the oppositehand for counter rotation and provided with four different operatingsections, the pitch in the first section of each feed screw matching thespacing of the nested articles, the length of the first section of eachfeed screw being sufficient to engage a plurality of the nested articlesbefore any separation action of the feed screws begins so as todistribute the weight of the articles over a plurality of articlesrather than only the bottom article of the stack thereby avoidingdistortion of the articles and permitting the lead edge of the feedscrews to enter the nested stack, each of said feed screws having asecond section having an increased pitch for separating the bottommostarticle of the stack, each of said feed screws having a third section inwhich the groove pitch is zero for 120° of screw rotation, and each ofsaid feed screws having a fourth section with a pitch approximatelyequal to the pitch of the first section, the axis of said feed screwsbeing inclined with respect to the vertical axis of the stack so thatthe grooves in said first section are substantially horizontal wherebythe articles ride substantially flat in the grooves.